On a single day in 2009, Ellen McCarthy became the wedding reporter for The Washington Post and broke up with her boyfriend of nearly two years. At age 30, she was suddenly a chick-flick cliche, interviewing florists and wedding planners between crying spells and dutifully smiling through conversations with blissful couples.

Fortunately, her book’s resemblance to a Katherine Heigl movie ends there. In “The Real Thing,” McCarthy never falls into a fountain, topples a wedding tent or spars with an infuriating groomsman who is actually perfect for her. Instead, she spends four years quietly standing in the corners of other people’s weddings in a simple black dress, taking notes. The result is a wise and compassionate look at how we love, along with some gentle suggestions for how we could get a little better at it.

‘The Real Thing: Lessons on Love and Life from a Wedding Reporter's Notebook’ by Ellen McCarthy (Ballantine)

The love-advice market is a crowded field, dominated by sassy know-it-alls — power-suited Dr. Joes and Janes smiling sternly on their book covers with their arms crossed; shrewd reality-television stars prolonging their 15 minutes by dispensing wisdom gleaned from their divorces. “The Real Thing” is a refreshing change, since McCarthy’s pumps-on-the-ground reporting focuses on happy couples, rather than the ones who bicker in therapists’ offices or in front of camera crews. She thus accesses a largely untapped resource: ordinary people who make mistakes but basically know what they’re doing.

We meet a young couple who fled India to marry out of caste, who always hold hands during arguments to keep tensions from escalating. There is the 57-year-old bride, widowed from her first marriage in her early 30s, who steadfastly refuses to remarry until she finds an equally good match. And an octogenarian couple, married 65 years, offer their secret to relationship longevity: “Be nice.”

That might sound like common sense, but common sense is in short supply in a category dominated by fear, blame and gamesmanship. McCarthy’s fieldwork gives her the authority to quietly shred many of the cultural myths that instill doubt and panic in both singles and couples. She observes that none of the brides and grooms she meets sealed the deal with feigned indifference or other machinations. To the contrary, their courtships were characterized by a distinct lack of mystery. When she asks her subjects what made them realize that they had found the right person, the most common word she hears is “comfortable.”

“Hollywood and romance novels can’t do comfortable: We’d fall asleep,” McCarthy writes. “Can you imagine a movie where two people meet, feel at ease with each other, and then mutually agree to transition into a committed relationship? Blech.”

Not that she thinks every couple she profiles is going to make it. In a hilarious chapter, she describes some red flags she encountered during her tenure. If a reporter asks what you love most about your future spouse, and your only response is “she’s hot” or “he’s rich,” you might want to look into getting that deposit back.

McCarthy weaves her own story throughout “The Real Thing” — from her heartbreak to her marriage to the birth of her first child. We learn that when she was single she would wake in the middle of the night, panicked that she’d never find her love; spending $10,000 to have her eggs frozen helped quell her anxiety. She describes the extremely unromantic way she met her husband — involving a hungover, post-party Facebook request. She also has a healthy sense of humor about a wedding reporter’s position in the newspaper hierarchy, at one point recounting the time she haplessly threw together a last-minute Judy Jetson costume for a Halloween masquerade wedding. “Am I even still a journalist?” she writes. “I don’t think Bob Woodward did this; this was not Joan Didion’s path.”

For the most part, McCarthy deftly balances the first-person confessional with sturdy professionalism. The autobiographical sections are relevant and charming, and she grounds her observations in psychological research. The clinical studies offer useful advice (I found myself making ticks next to some of her marriage tips and noting, “must remember to do this”), but the chapters centered on them feel more familiar than those based on her original reporting.

And there are times when the book is a little too sweet. In a couple of funny chapters she provides short bullet points of relationship and wedding don’ts. (On receiving lines: “This is not Space Mountain. Do your guests really have to queue up just to get the chance to talk to you?”) They’re great, but they leave you wanting a bit more dish. One wishes to see the Ellen McCarthy who kicks off her heels and shares a cigarette at 2 a.m., offering opinions not fit for the mother of the bride’s ears.

Then again, maybe it’s for the best — if you want bad-marriage voyeurism and bridezilla-bashing, you’ve got plenty of other options. McCarthy has done something rare: She has written an optimistic book about love that is clear-eyed and unsentimental. And unlike the exasperated purveyors of laws, codes and 12-point action plans, she knows that there is really no such thing as an expert on love. Clinical studies can show us pieces of the elephant, but we’re all fumbling in the dark. By studying everyday people confronting life’s most puzzling subject, McCarthy reveals how much natural wisdom is out there. She offers hard evidence that success in love is not predicated on being particularly sexy or savvy, but instead grounded in homelier virtues like kindness, courtesy and a willingness to let the other guy win.